3 Executive Summary The flooding in parts of England in 2007 gave a renewed focus to flood risk management. The Mayor is aware that flood risk is a major issue for London and that if the rainfall seen elsewhere in England in 2007 had fallen on London, it would have triggered a major civil emergency. The likelihood of flood is increasing with climate change. The potential consequences of flooding are also increasing as London s population continues to grow. This RFRA, combined with the policies in the draft replacement London Plan and a range of actions being undertaken by various organisations, aims to ensure that overall flood risk (probability x consequences) does not increase and that by addressing existing problems, overall risk is reduced. Managing flood risk in London cuts across the responsibilities of many organisations. Whilst the Environment Agency has the lead responsibility, it is clear that co-ordinated actions/policies and collaborative working are required to manage and minimise the risks. This RFRA contains 19 recommendations, involving or lead by a range of organisations. Progress against the recommendations will be monitored annually in the London Plan Annual Monitoring Report. page 3 of 62

4 Chapter 1 - Introduction Regional Flood Risk Appraisal (RFRA) 1. Flood risk is a major issue for London. Diagram 1 illustrates that 15% of Greater London has some extent of known tidal and/or fluvial flood risk. The issue of flood risk has become increasingly recognised over recent years with much publicised floods during the 1990s and early part of the 21 st century. This has followed a long period when major floods did not affect London and when, consequently, flooding had not received a high profile in matters relating to land use planning. Previous notable floods occurred in 1947 and 1953, each of which resulted in responses to increase flood protection through capital projects. The publication of PPG25 in 2001 marked a step change in the approach to flood risk management in the planning system. 2. In December 2006 PPS25 (Planning Policy Statement 25 Development and Flood Risk) was published. It continues to raise the profile of flood risk management amongst land use and planning considerations. One of the key elements it introduces is the requirement for Regional Planning bodies to produce a RFRA to accompany Regional Spatial Strategies. This fits in to a hierarchy of Flood Risk Appraisal: Hierarchy of Flood Risk Appraisal Flood Risk Management Applicable to Prepared by Tool Regional Flood Risk Appraisal Regional Spatial Strategy Regional Planning Body Strategic Flood Risk Assessment Local Development Document or Area Action Plans Local Planning Authority Flood Risk Assessment Specific sites Developer/land owner 3. According to PPS25 a RFRA should include a broad consideration of flood risk, informed by appropriate operating authorities. This RFRA has been undertaken with the assistance of the Environment Agency. In 2008 Government published a Practice Guide to PPS25 This is useful in highlighting how best to implement PPS This RFRA deliberately crosses the boundary between land use planning and emergency planning, as suggested in the PPS25 Practice Guide. This has been done as the Mayor recognises that there is not always close liaison between the two disciplines and it will be important to stimulate greater links between them. The London Resilience Team has recently published its draft London Strategic Flood Plan (LSFP). This seeks to co-ordinate emergency services and emergency planners across London in the event of a major flood. This is the first time it has been updated since the opening of the Thames Barrier. It will be important to foster links between the RFRA and the LSFP. 5. The Environment Agency is the national lead on flood risk management and has produced or is producing further research which has been an important input to this Appraisal. page 4 of 62

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6 Progress since Draft RFRA 6. In June 2007 the Mayor issued a draft RFRA for consultation. Since then a number of key events have taken place. The floods of summer 2007 and the subsequent Pitt Review are key but there are also some proposed changes to PPS25 that Government is currently consulting on and continued progress by Environment Agency on Catchment Flood Risk Management Plans and TE2100. Consultation 7. The following organisations responded to the Consultation: Environment Agency London Borough Barking & Dagenham London Borough Greenwich London Borough Haringey London Borough Richmond Upon Thames London Development Agency London Fire and Emergency Planning Authority London Fire Brigade Thames Water Transport for London 8. The consultation was just prior to a series of major floods across England, particularly affecting Gloucestershire, Humberside and parts of Yorkshire. London suffered relatively minor flooding, however, the flooding acted as a wake up call for both London and the country as a whole. There can be no doubt that if the extremely high volumes of rainfall that affected some parts of the country had fallen across London, there would have been huge disruption, damage and danger to life that would have taken months, possibly years to have recovered from. 9. The Government quickly announced a review of flood risk, this was the Pitt Review This examined all aspects of flood risk management from forecasting and warning, to flood event management and evacuation/rescue to recovery and rehabilitation. 10. The publication of this RFRA has been delayed to take account of the Pitt Review, whose final report was published in June 2008 and the Government s response to the report. The London Plan 11. The London Plan was originally published in It was reviewed twice during , resulting in the publication (Feb 2008) of the London Plan Consolidated with changes since The Draft RFRA informed the Feb 2008 London Plan. The Mayor has now published a draft replacement London Plan, October 2009 with the intention of publishing a Replacement London Plan in late The findings of this RFRA have shaped the policies within the draft replacement London Plan and the policy references contained in this RFRA are taken from that document. Flood risk is recognised as an important consideration for all developments and in combination with PPS25, policy 5.12 sets out the strategic approach in London. Flood risk is also referred to in relation to several of the Opportunity Areas where there page 6 of 62

7 is known to be a particular risk. Flood risk has been an important constraint in identifying capacity for housing in London through the Strategic Housing Land Availability Assessment (SHLAA). Sites with a known flood risk had their capacity reduced depending upon the severity of the risk and no sites within the functional flood plain (zone 3b) or greenfield zone 3a sites were identified as having housing capacity. The Sequential Test 13. PPS25 contains a sequential test to ensure that development takes place in the areas available at lowest flood risk. London is a unique city in the UK. It is heavily built up with a tightly drawn administrative boundary. The Green Belt policy is now long standing and has been largely successful in its aims of preventing London from spreading, preventing the coalescence of peripheral settlements and protecting open countryside. This success is now reaping the additional benefit of promoting the re-use and regeneration of brownfield land which is widely seen as an important element in achieving sustainable development. In some places that were generally undeveloped in the middle of the 20 th Century, the Green Belt extends into London, for example in the Lee Valley. Other significant open spaces are also protected by the land use planning system with various levels of policy; the highest of these, Metropolitan Open Land (MOL) provides a similar level of protection to Green Belt. 14. The delineation of the Green Belt and the other protected open spaces in London mean that the scope for new development on land other than brownfield redevelopment land is extremely limited. Over recent years, monitoring (London Plan Annual Monitoring Reports) has indicated that over 96% of new development has been on brownfield sites. The vast majority of future development in London is therefore expected to take place on brownfield land. 15. Many of London s remaining large brownfield areas are either substantially or partially within flood zones. Diagram 4 demonstrates that 42% of the area of Opportunity Areas and 24% of the area of Intensification Areas are within known flood zones. However alternative sites for large scale development within London do not exist without encroaching into Green Belt, MOL or other protected spaces. 16. The SHLAA exercise examined the potential housing capacity of over 10,000 sites within London. Flood zone 3b and greenfield zone 3a sites were excluded as a strategic approach to the sequential test. It is clear however, that in order to meet London s housing need, consideration will have to be given to brownfield zone 3a sites. 17. Therefore from a strategic perspective, the sequential test permits the consideration of these sites for development. It will still be necessary for boroughs and developers to apply the sequential test locally and consider flood risk assessments at a more detailed level when allocating uses or applying for planning permission. It will still remain important to place more vulnerable uses in areas with lower flood risk in order to meet the Sequential Test at a local level. How to use the RFRA 18. The RFRA is a strategic overview of flood risk across London. It does not represent a detailed analysis of flood risk in relation to any particular areas or sites. It contains a series of recommendations which are either region wide, applicable to boroughs in undertaking their SFRAs or apply to utility/service providers. Progress against these recommendations will be reported annually in the London Plan Annual Monitoring Report, normally published in February. page 7 of 62

8 19. The RFRA will remain a live document with regular updates to reflect the changing position in relation to both climate change and development pressure and policy responses. The first anticipated review will be in early 2012 to reflect the final replacement London Plan and in general reviews should be no less frequent than every 5 years. 20. The RFRA should be useful to spatial planners, developers, infrastructure and utility operators and emergency planners. It is a specific aim of this RFRA to bring spatial planners and emergency planners into closer communication. page 8 of 62

9 Chapter 2 - Overview of Flood Risk 21. London is exposed to 5 different potential sources of flooding. These are analysed below, each has different spatial impacts on London and requires a different set of responses. Some responses relate to the land use planning system, whilst others relate to broader spatial matters or operational considerations for a range of organisations. Each type of flooding is analysed by examining: Nature of the risk Development locations that may be affected Information available Broad flood risk management options The likely impact of climate change Strategic recommendations 22. Chapter 3 goes on to consider flood risk in relation to key locations and infrastructure in London. In this way the RFRA represents an examination of both the potential future flood risk issues and the existing flood risk issues that affect London. By doing this it can make recommendations that fulfil one of two functions. Firstly, how to ensure that future flood risk is minimised and any residual flood risks are managed appropriately. Secondly, to promote new development that will help to reduce and manage existing flood risks. This approach is in line with PPS25. Tidal Flood Risk Nature of Risk 23. The River Thames and the lower reaches of some of the tributary rivers are affected by the tide. The River Thames has a very large tidal range, in excess of 7 metres on spring tides. The tide s influence reaches to Teddington Lock on the Thames and up several tributaries, for example as far as Lea Bridge on the River Lee. 24. Without the current river walls many areas of London alongside the Thames and along the tidal stretches of the tributaries would be inundated twice a day through the normal tidal cycle. River walls have been steadily built up since Roman times to give increasing levels of flood protection and to enable urban development. 25. The particular threat that has remained is from tidal surges. These occur when a combination of high tide, easterly winds and a weather system depression over the North Sea can cause the tide levels to increase significantly above the normal tidal range. Previous incidents of this type of flood risk date back to More recently, in 1928, 14 people were drowned in Westminster; this was the last time that central London suffered tidal flooding. In 1953 London was largely spared the impacts of a devastating tidal flood that cost the lives of over 300 people in the East of England. If that flood had funnelled further up the Thames the results could have been even more disastrous. 26. The area at risk of tidal flooding, including from storm surges approximates to the 5 metre contour line and is shown on Diagram 1. The area of London below the normal high tide range is approximately 6200ha and affects parts of 12 London boroughs. The area that could potentially be affected by a storm surge of the same magnitude as the 1953 flood covers ha and affects parts of 20 London boroughs. page 9 of 62

10 27. As a result of the 1953 flood, a system of flood defences was constructed. The most iconic element of this is the Thames Barrier, which has been operational since There are also around 400 smaller barriers and movable flood gates downstream of the Thames Barrier and over 300km of river walls and embankments stretching into Essex and Kent that have been raised by 2 metres to give additional protection from storm surges. Upstream of the Thames Barrier river walls are still necessary to prevent the normal range of high tides from flooding parts of inner and central London. This system of tidal flood defences made allowance for sea level rise and London is therefore protected to a very high level. It is estimated that the level of protection will reduce down to standard of 1 in a 1000 year (0.1% chance per year) by 2030 and this will continue to decline if no further measures are taken. 28. Since its completion in 1982, the Thames Barrier has been closed 116 times (up to September 2009) to prevent flooding. Diagram 2 below indicates that the number of closures per year is fairly variable; however, there is a general increase in the number of closures. This ties in with climate change observations. Closure of the Thames Barrier also necessitates closure of other barriers and flood gates, prevents navigation and restricts the ability of other vessels to moor or unload cargoes downstream of the Barrier. The Environment Agency has indicated that closing the Thames Barrier more than 70 times in a year is not likely to be sustainable. 29. There are residual risks even given the high standard of flood risk management measures that are in place. These risks are two fold either from an overtopping of the defences ie a larger event than has been planned for or by a breach in the defences ie a failure, either accidental or deliberate of the defences. The likelihood of such residual risks are very small however, the scale of consequences from rapid inundation and deep water in heavily urbanised areas mean that these residual risks must be considered. Diagram 2 Thames Barrier Closures page 10 of 62

11 Locations 30. The tidal flood risk area through London affects areas to the north and south of the Thames and up some of the tributary rivers. Given that much of the land alongside the Thames in central and inner London has been in active urban uses for centuries, it is not surprising that there is a lot of infrastructure already in place there although it is protected to a high standard by the combination of the river walls and the Thames Barrier. 31. In north east and south east London there are large areas of derelict or under used land forming the Thames Gateway. These areas have mostly been in industrial uses, many of which have now ceased or are declining. These areas make up some of the major opportunities for London to accommodate its own growth pressures. Being alongside the river it is to be expected that many of these areas will have an associated element of flood risk. Despite their derelict, underused or industrial nature these areas are also protected from flooding to a high standard. Information available 32. The 1 in 1000 year tidal flood envelope is shown on diagram 1 and covers a wide area. It is closely related to the 5m land contour. This area is currently defended to a high standard by the combination of flood walls and embankments and the Thames Barrier and other movable gates and barriers. 33. The condition of flood defences is held on a database by the Environment Agency which carries out regular inspections to update the condition survey and take appropriate action either directly or through the structure owners to ensure that structures are in a sound condition. The vast majority of flood defences along the Tidal Thames are in a good structural condition. 34. The East London Strategic Flood Risk Assessment covers the Thames Gateway boroughs and is available from London Thames Gateway Partnership. It provides a good sub regional overview of flood risk including the impacts of a number of breach locations. Flood Risk Management options 35. Flood defences for the Thames Estuary have been built up over hundreds of years and have tended to respond to flood events by successively raising the height of flood defences walls and embankments. The current defences were constructed through the 1970s and 1980s in response to the tidal surge of 1953 and include the Thames Barrier as the most iconic element of the defences. There are also many other flood gates and moveable structures that make up the defence system. This system of tidal flood defences was designed in the knowledge of sea level rise and it made allowances for this. Therefore protection to the 1 in 1000 year event is estimated to be given until 2030, after which the level of protection will decline below 1 in 1000 years unless other measures are taken. 36. The Environment Agency is undertaking the Thames Estuary 2100 (TE2100) project. This is the first time that planning for future flood risk management is taking place in anticipation of future flood risk rather than in response to a flood event. The consultation on TE2100 took place in April-June This RFRA takes account of the page 11 of 62

12 policy initiatives in that draft. The final plan will be published in 2010 and this RFRA will be updated to incorporate any significant changes. 37. TE2100 indicates that the present system of flood risk management for tidal flooding can continue to provide an acceptable level of risk management up to 2030 without major alterations. Beyond 2030 more actions will be needed: : Work with Local Authorities and the construction industry to ensure that existing and new development is safe through spatial planning and local resilience measures Prepare joint riverside strategies establishing a shared vision for the riverside Continue to maintain, enhance, improve or replace existing flood management systems Work with Local Authorities and communities on the future use of the Thames Barrier in managing fluvial flooding in West London Continue flood forecasting and emergency planning activities Commence the creation of new inter-tidal habitat in the Lower estuary which is being lost as sea levels rise : Maintain, improve or replace the walls, embankments, barriers and gates along the Estuary. Work with Local Authorities and communities on enhancing and revitalising the Thames riverside Continue flood forecasting and emergency planning activities Continue replacing areas of inter-tidal habitats as sea-levels continue to rise Decide on and construct the option to manage increasing flood risk for the end of the Century and beyond : End of the century option operational (see ). Further raising and adaptation of defences where required to keep new Barrier closures to within operational arrangements Continue programme of maintenance replacement and repair of upstream and downstream defences Continue flood forecasting and emergency planning activities 38. These actions will be easier, more affordable and more sustainably delivered if they are planned for from today. The Environment Agency has identified four broad areas (Reaches) of the Thames and have outlined the following general spatial options, it will be important for SFRAs and new developments to identify methods of implementing these options: West London Reach (Teddington Lock to Hammersmith Bridge) 39. Enhanced channel capacity to cope with fluvial flood flows. Pursue options for small scale set back of development from river walls to enable river walls to be modified, raised and maintained in a sustainable, environmentally acceptable and cost effective way. City Reach (Hammersmith Bridge to Thames Barrier) page 12 of 62

13 40. Pursue options for small scale set back of development from river walls to enable river walls to be modified, raised and maintained in a more sustainable, environmentally acceptable and cost effective way. Regeneration Reach (Thames Barrier to Tilbury Docks) 41. Pursue options for small scale set back of development from river walls to enable river walls to be modified, raised and maintained in a more sustainable, environmentally acceptable and cost effective way. In some cases there may be opportunities for larger scale set back as part of development in the Thames Gateway. 42. Large areas of currently undeveloped land such as Rainham/Wennington Marshes, Erith Marshes and Dartford/Crayford Marshes could be used as Strategic Flood Storage areas to use as emergency storm surge flood storage. Lower Estuary Reach (Tilbury Docks to Southend) 43. This is outside London but options sited here could protect London. This area may provide environmental mitigation and compensation for impacts inside London. Confluences 44. Particular care will be needed when examining the confluences of tributary rivers with the Tidal Thames given the interaction between the different systems. In particular there may be particularly severe effects when a high tide combines with peak fluvial flows. In general the flood defences have been built to a very high standard and therefore these area share high levels of flood risk protection. 45. The draft replacement London Plan promotes the set back of development as suggested for all three London Reaches (Policy 5.12). The open space areas are also protected by other mechanisms such as Green Belt Policy within Chapter 7. The Likely Impact of Climate Change 46. Climate Change will have a major impact on the tidal flooding threat. The rising sea level will steadily reduce the level of protection that defences offer. The predictions for how quickly sea level will rise vary considerably depending on the assumptions used about emissions and climate modelling. The TE2100 project has considered a range of climate change derived sea level rises from 0.9m (Defra 2006 Climate Change Scenario) to 4m (High++ Level where all conceivable sea level rise contributions up to 2100 occur). 47. Up to 2030, i.e. to the end of the timeframe of the replacement London Plan, there are limited differences between predictions and existing flood risk management options can continue to provide appropriate risk management for tidal flooding. Beyond 2030 there is more variation in the projections. However it is clear that by starting to plan for these changes now, the ability to cope with more extreme situations will be improved. This is the aim of the London Plan policies. Strategic Recommendations Recommendation 1 All Thames-side planning authorities should consider in their SFRAs and put in place DPD policies to promote the setting back of development from the edge of the Thames page 13 of 62

14 and tidal tributaries to enable sustainable and cost effective upgrade of river walls/embankments, in line with Policy 5.12, CFMPs and TE2100. Recommendation 2 The London Boroughs of Richmond, Kingston, Hounslow and Wandsworth should put in place policies to avoid development that would prejudice the implementation of increased channel capacity between Teddington Lock and Hammersmith Bridge in line with TE2100 findings. Recommendation 3 The London Boroughs of Havering and Bexley should put in place policies to prevent development that would prejudice the use of Rainham/Wennington Marshes, Erith Marshes and Dartford/Crayford Marshes for emergency flood storage in line with TE2100 findings. Although outside London, Thurrock and Dartford should also consider this aspect of flood risk management. Recommendation 4 Boroughs at confluences of tributary rivers with the River Thames should pay particular attention to the interaction of fluvial and tidal flood risks. These are Havering, Barking & Dagenham, Newham, Tower Hamlets, Greenwich, Lewisham, Wandsworth, Hounslow, Richmond and Kingston. page 14 of 62

15 Fluvial Flood Risk Nature of Risk 48. London has many tributary rivers leading to the river Thames and the Thames itself is a fluvial river upstream of Teddington Lock. These are shown on Diagram 1. As with any river system there is a possibility that any of these rivers could flood. This could come from either particularly intense rainfall within the catchment or from a blockage or restriction to flow within the river channel. 49. The Environment Agency have produced Catchment Flood Management Plans (CFMP) for fluvial rivers in England and Wales. These CFMPs examine the characteristics of rivers, current and future flood risk and potential flood risk management measures and set out a long term view of flood risk ( years). The CFMPs relevant to London are: Thames CFMP July 2008 North Kent Rivers CFMP September As a predominantly urban area London s rivers are often heavily modified from their natural state. This means that rivers have been straightened, deepened, widened and constructed from materials such as concrete. These changes have often been made specifically to reduce the risk of flooding by either increasing the physical size of the river channel or increasing the rate at which it can convey water. 51. The urbanised river environment also contains many bridges, tunnels and culvert structures. These culverts are often underneath roads or railways but sometimes flow under substantial areas of land. These form potential flood risks as they can become blocked or restricted through litter or more likely larger debris such as shopping trolleys, mattresses or even vehicles. Culverts present a particular difficulty in that it is difficult and expensive to determine their condition and to carry out maintenance and repairs. It can also be difficult to ascertain ownership and maintenance responsibility for some culverts. It is also known that there are a significant number of illegal mis-connections of foul sewers to surface water culverts, these lead to ongoing pollution of rivers. In general opportunities to remove and open up culverts should be taken on environmental and aesthetic grounds as well as improving flood risk management. This is required in draft replacement London Plan policy In London the rate at which rainwater enters urban rivers is significantly higher than normally occurs naturally. This is because a larger proportion of London s surface is covered by hard impermeable surfaces which are positively drained via surface water sewers into local watercourses and then to larger tributaries. This also increases the absolute volume of rainwater that reaches rivers because there is less chance for water to soak into the ground, being taken up by vegetation or evaporate. 53. Such urban rivers respond very rapidly to rainfall and the opportunity for flood warnings to be issued is limited to as little as ½hr to 2 hrs in many cases. Some larger rivers such as the Lee or the fluvial Thames have much bigger upstream catchments so that flood flows can be detected several hours or even 1 or 2 days in advance, allowing for reasonable flood warnings to be issued. Canals 54. London has many miles of canals. In general canals pose a low flood risk as they have limited surface water inputs. However the Grand Union Canal alongside the Colne page 15 of 62

16 Valley and the River Lee Navigation are both intricately linked to large fluvial catchments and may convey flood waters from fluvial sources. A further consideration is that any canal which is on land higher than the surrounding land has the potential for a breach. Therefore consideration of flood risks from canals needs to be factored into SFRAs and FRAs. Locations 55. Fluvial flooding affects parts of most London boroughs. As such it affects a number of Opportunity Areas, town centres and strategic infrastructure across the city. In general the scale is much smaller than tidal flooding. Fluvial flooding has been more frequent than tidal flooding meaning that many areas of floodplain have been left undeveloped, often forming parks within the wider urban setting, the most prominent example being the Lee Valley Regional Park. Information available 56. The flood risk zones are shown on Diagram 1. The Environment Agency also has modelled floodplains for some of the tributaries. Most tributaries have been modified to reduce the likelihood of flooding. In many cases these consist of raised river walls and widened channels. In the case of the River Lee an entire new flood relief channel was constructed along the east side of the Lee Valley in the 1970s. These channel modifications have generally resulted in a reduction of biodiversity value and amenity value and an increased maintenance requirement. 57. The Catchment Flood Management Plans classify flood plains into 6 broad types: Undeveloped natural flood plain Developed flood plain with no built defences Developed flood plain with built defences Developed flood plain with typically concrete river channels Major urban expansion in or close to flood plains Narrow flood plains and mixed use land 58. The CFMPs then identify five policy options to manage flood risk and the key messages that are relevant to each of these approaches. 59. These approaches are applied to policy units (sub-regional areas) that have been identified by geography, floodplain characteristics and land use types. More detailed actions for each policy unit, reflecting the relevant approach, have been identified to manage flood risk, today and in the future. These actions can be split into two types: those that help to reduce the likelihood of flooding occurring and those addressing the consequences if a flood does happen. 60. Three of the five policy options are used in London and they are specified below in relation to each of the catchments. SFRAs and FRAs should consider how to implement these policy approaches in local circumstances. 61. One of the main messages relevant to many of the London rivers is that redevelopment provides an opportunity to reduce flood risk. Draft replacement London Plan Policy 5.12 provides the scope to realise these opportunities. page 16 of 62

17 London Catchments (local authorities in italics are outside London but relevant to the management of the catchment) Each tributary river system in London has different attributes, these are described below: River Lee - Boroughs affected: Barnet, Enfield, W Forest, Haringey, Hackney, Tower Hamlets, Newham 62. The River Lee catchment is a mixture of relatively small urban tributaries with very fast reaction times to flood and the main river Lee channel which has a large and substantially rural upstream catchment. The River Lee suffered extensive flooding in 1947 as a result of rapid snowmelt. In the 1970s the River Lee Flood Relief Channel was completed to reduce the risk of flooding through the Lee valley. It is known that the design specification for the River Lee Flood Channel was to accommodate a 1 in 70 year flood. This is below the level of protection that is now required for development under PPS25. Furthermore the level of protection is likely to have been reduced further by the extensive development in the Hertfordshire and west Essex upper catchment of the river Lee. It will therefore be important for the current level of flood protection through the Lee Valley to be re-assessed. This is particularly relevant given the extent of built development (including raised reservoirs) in the natural flood plain and the fact that there are considerable development proposals both within and outside London. 63. The Lee catchment also includes several tributaries which have experienced localised flooding, notably Salmons Brook, Ching Brook, Turkey Brook and Pymmes Brook. These are all highly urbanised catchments where flood risk needs to be addressed strategically. 64. The CFMP recommends an approach to take further action to reduce the risk of flooding (now and/or in the future) for the main River Lee river channels. For the tributaries to the Lee the CFMP recommends taking action to increase the frequency of flooding on open spaces to deliver benefits locally or elsewhere, which may constitute an overall flood risk reduction. River Roding - Boroughs affected: Barking & Dagenham, Redbridge, Newham 65. The river here was extensively re-engineered during the 1980s and 1990s in conjunction with the construction of the North Circular Road and M11 and the introduction of a semi-tidal barrage in Barking. There has been localised flooding within London in recent years although most regular flooding occurs on agricultural land north of the London boundary. It would prove useful to examine the strategic flood risk along the length of the river Roding. The Environment Agency has prepared a River Roding Flood Risk Management Strategy. 66. For the London reaches of the River Roding, the CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). River Rom/Beam - Boroughs affected: Barking & Dagenham, Havering 67. There has been limited localised flooding in this catchment and the Beam wetlands serve as a strategic flood storage area. Development proposals will still need to consider their flood risk. page 17 of 62

18 68. The CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). Ingrebourne - Boroughs affected: Havering, Brentwood 69. There has been some localised flooding to properties in Upminster and other flooding on open spaces through the river valley of this relatively natural tributary. There is also the tidal interaction where the southern part of the river becomes tidelocked at high tide. 70. The CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). Brent - Boroughs affected: Barnet, Brent, Harrow, Ealing, Hounslow 71. The River Brent and its various tributaries have suffered localised flooding, particularly in the upstream catchments of Harrow and Barnet. The Environment Agency has examined options to address this. These options should be examined and recommendations incorporated into SFRAs and LDD policies and form local policy objectives of reducing and storing surface water run-off. The Brent flows through extensive park areas offering opportunities for some flood risk management. 72. The CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). Crane - Boroughs affected: Harrow, Hillingdon, Ealing, Richmond, Hounslow 73. This river has historically suffered flooding problems in its lower reaches. The upper Reaches, known as the Yeading Brook, flow through considerable lengths of parks and open spaces giving some less sensitive areas for floodwater to be accommodated. Nevertheless a strategic examination of options for sustainable surface water management, bearing in mind climate change predictions, should be used to influence future development decisions and considerations of the management of the riverside open spaces. 74. The CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). River Colne and Pinn - Boroughs affected: Harrow, Hillingdon, Spelthorne 75. The Colne is a large tributary which in places forms London s western boundary. It has suffered extensive flooding in the past, although mostly of undeveloped land. Flood alleviation works have been undertaken. The River Pinn has had several recorded localised floods over recent years. 76. For the River Colne, the CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change) and for the Pinn it recommends taking action to increase the frequency of flooding on open spaces to deliver benefits locally or elsewhere, which may constitute an overall flood risk reduction. page 18 of 62

19 Hogsmill Brook - Boroughs affected: Kingston, Epsom & Ewell 77. Some localised flooding has occurred on this river, notably through Kingston Town Centre. Most of the route of the river flows through open spaces and parts of the Green Belt. 78. The CFMP recommends taking action to increase the frequency of flooding on open spaces to deliver benefits locally or elsewhere, which may constitute an overall flood risk reduction. Beverley Brook - Boroughs affected: Richmond, Wandsworth, Kingston, Merton. 79. Many parts of the floodplain remain as open space, notably through Richmond Park, although the Raynes Park area is identified as having an extensive floodplain. This coincides with the confluence of two tributaries and the river passing underneath several major road and railway structures. 80. The CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). Wandle - Boroughs affected: Wandsworth, Merton, Sutton, Croydon. 81. The downstream area of this river catchment runs through a heavily built up area with flood plain covering significant areas of already developed land. Some upstream areas south of Mitcham are more open with the possibility of enabling some upstream catchment storage. 82. The CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). Ravensbourne - Boroughs affected: Lewisham, Bromley, Greenwich 83. This is a relatively large river with several tributaries. In the downstream reaches the river is tightly confined by urban development although in the more southerly upstream reaches the river and its tributaries often flow through open spaces. The river has benefited from river restoration projects in recent years which have also improved flood risk management. 84. The CFMP recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). River Cray/Darent - Boroughs affected: Bexley, Bromley, Greenwich, Dartford 85. The upstream reaches stretch out into the Green Belt. Through much of the middle reaches the river runs through a mix of built up areas and open space and in the lower reaches there are extensive areas of floodplain and the interaction with the tidal Thames presents a further flood risk although the Dartford and Crayford marshes provide large areas of flood storage. 86. These catchments are covered by the North Kent Rivers CFMP which recommends an approach to take further action to reduce the risk of flooding (now and/or in the future). page 19 of 62

20 Marsh Dykes boroughs affects Bexley, Greenwich. 87. There are a number of modified and natural rivers in the Thamesmeand/Belvedere area which are unusual in that they are below the height of Thames flood defences and rely on storage reservoirs and pumped discharges. 88. TE2100 recommends an approach to take further action to sustain current scale of flood risk into the future (responding to potential increases in flood risk from urban development, land use change, and climate change). Furthermore it recommends careful consideration of new development given the particular risks of this low lying area and the difficulties in managing surface water following heavy rainfall events. Fluvial River Thames- boroughs affected: Kingston, Richmond, Spelthorne, Elmbridge 89. The fluvial reaches of the Thames are prone to large flood events from its extensive upstream catchment. There are no built flood defences and this stretch of the river is particularly noted for its historic and cultural value. Given the large upstream catchment close co-operation is needed with flood management further west. The Environment Agency is developing the Lower Thames Flood Risk Management Strategy. 90. The CFMP recommends an approach to take further action to reduce the risk of flooding (now and/or in the future). Flood Risk Management options 91. Now that the CFMPs policy approaches have been determined, there needs to be continued work to ensure that these policy approaches are implemented. The actual detail of how these need to be implemented will require careful consideration of the local river and its flood plain characteristics. Draft replacement London Plan policy 5.12 sets out the strategic policy of managing flood risk through new development. In many cases setting development back from river edges will enable a range of flood risk management options to be used. This should enable the most sustainable, aesthetically pleasing and cost effective options to be selected. 92. Boroughs and individual developments will need to consider the sequential test and allocating more vulnerable land uses in areas of lowest risk. 93. Open spaces within development can be designed to accommodate flood waters. The Green Grid concept in East London is a good example. In some cases the flood risk is such that upstream flood storage may prove to be the most realistic option. Efforts to restore damaged river environments also present good opportunities to improve flood risk management. Such measures will need to be considered in conjunction with neighbouring local authorities and indeed regions. 94. Where a residual flood risk remains, flood risk assessments should consider what would happen to the development and its users/occupants if a flood were to occur and how the development would recover from the flooding. 95. Surface water should generally be managed at source. Large development locations offer particular opportunities to make significant changes to surface water management to become more sustainable. The Likely Impact of Climate Change 96. Climate change predictions suggest that there will be an increased risk of flooding on tributary rivers due to more intense patterns of rainfall. Most predictions estimate page 20 of 62

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